Mighty Module Model DIS874
Thermocouple Input Process Indicator

Description

The DIS874 provides a display, optional isolated DC output voltage or current proportional to any thermocouple input signal, and optional alarm setpoints.  The units include filtering and conditioning to reduce susceptibility to transients and noisy operations.  The digital display utilizes an auto-zero dual-slope integrating A/D converter for accuracy and stability.

All controls are accessible by removing the gasketed front access panel.  The display controls are wide ranging so that they can be calibrated to display engineering units.  Decimal point selection is made with a switch, also accessible from the front.  A complete set of engineering unit labels is sent with each DIS.  Once the display has been adjusted to read the correct engineering units, the alarm setpoints can be adjusted without test equipment and without disturbing the output voltage or current.

Either setpoint may be displayed by use of the SP CAL switch. Each setpoint has an LED to indicate alarm status.  The alarms have adjustable deadbands.  Terminations are made to a screw terminal connector on the rear of the case.

Upscale burnout protection is provided as standard.  In the event the thermocouple opens, the unit responds as thought the input is offscale high.  Option B provides downscale burnout protection (unit responds as though the input is low).

The standard DIS874 and DIS974 provide thermocouple linearization using analog circuitry, which has certain limitations.  Analog linearization specifications are summarized in Table 1.  Option LL, digital linearization, provides superior performance as listed under the specifications.

Typical Applications

Temperature indication, monitoring, control, data acquisition, HI/LO control, etc.

Mounting

The DIS is designed to be mounted from the front of a panel through a standard horizontal 3.62 x 1.77 inches (1/8 DIN) cutout.  Two mounting cam-screws secure the DIS to the panel.

Specifications

INPUT RANGE select any type thermocouple   (minimum span 4 mV) OUTPUT RANGE Voltage   select any range between ±10 V     10 mA max load     (min span 0.2 V) Current   select any range from 0 to 20 mA max     24 V compliance**     (min span 1 mA) OPEN SENSOR OUTPUT >= full scale RELAY CONTACTS (spdt) Resistive Load:   5 A max, 150 W max,   240 VAC max, 30 VDC max Inductive Load:   1/8 HP max at 120/240 VAC SETPOINT each alarm 0 to 100% of span DEADBAND 0.25% to 100% of span RESPONSE TIME <= 100 ms   (range dependent) ISOLATION Output/Input   >500 megohms Breakdown Voltage   >600 VAC rms POWER 115 VAC ±10%, 50/60 Hz   (4 W max) 230 VAC ±10%, 50/60 Hz   (4 W max)

DISPLAY Digit Size   .56 inch LED, 3 1/2 digits, ±1999 Decimal Point   ±1.9.9.9 Control Range   Zero     ±1999   Span     min span 10     max span 2000 Display Update   3/sec ACCURACY ±0.1% of span LINEARITY Standard   See Standard Linearization Tables Below Option LL    ±2ºC (3.6ºF) or better   ±0.05ºC (0.9ºF) for types    J, K, T, E or N if range is   between -200 and +200ºC     (-328 and +392ºF) OUTPUT RIPPLE <0.1% of span   (peak to peak) COMMON MODE REJECTION 120 dB, DC to 60 Hz OPERATING TEMPERATURE  14ºF to 140ºF -10ºC to 60ºC TEMPERATURE STABILITY ±(0.02% of span +30 µV)/ºC max

STANDARD LINEARIZATION ACCURACY, BASE-METAL THERMOCOUPLES
ZERO-BASED RANGES			LOW-TEMP RANGES  (HIGH END 0ºC)
T/C TYPE	LIMIT FOR ±1% OF SPAN	LIMIT FOR ±2% OF SPAN	LIMIT FOR ±0.5% OF SPAN
E	0/500ºC 32/932ºF	0/1000ºC 32/1832ºF	-100/0ºC -148/32ºF
J	0/1000ºC 32/1832ºF	0/1200ºC 32/2192ºF	-100/0ºC -148/32ºF
K	0/800ºC 32/1472ºF		-100/0ºC -148/32ºF
Cannot Linearize Type K Above 800ºC (1472ºF) See Option LL above
N	O/500ºC 32/932ºF	0/1200ºC 32/2192ºF	-100/0ºC -148/32ºF
T	0/400ºC 0/752ºF	0/400ºC 0/752ºF	-100/0ºC -148/32ºF

STANDARD LINEARIZATION ACCURACY, PLATINUM THERMOCOUPLES
T/C TYPE	ZERO-BASED RANGES	ELEVATED-ZERO RANGES
B	-N.A.-	±3% of span for  500/1820ºC (932/3308ºF) ±1.5% of span for 800/1820ºC (1472/3308ºF)
R	±2.5% of span or better, any zero-based range	±1.5% of span or better, any range starting above 200ºC (392ºF)
S	±2.5% of span or better, any zero-based range	±1.5% of span or better, any range starting above 200ºC (392ºF)

       
* Within specified range limits.

** Compliance:  The sum of the voltage drops in the output loop cannot exceed 24 V at rated current 
    (1200 ohms at 20 mA).